水面散热的焓差公式及其应用

Enthalpy difference formula for calculating heat dissipation on water surface and its use

我国现在所用的水面散热公式,包括蒸发散热、对流散热、辐射散热三部分,以此为基础建立的计算蒸发系数的通用公式是有缺陷的,其中不应包含水气温差。因为水气温差是对流散热的推动力,而蒸发散热只传质,不传热,只产生汽化潜热,所以不应有对流散热的成分。产生上述问题的原因是在实验中蒸发散热和对流散热是不可分的,本文将蒸发散热和对流散热合为一个公式,提出用焓差公式来整理试验资料,给出了以焓差为推动力的散热公式,使原有计算公式得到简化,更符合实际。

The current formula in China for calculating heat dissipation on water surface is consists of three parts:evaporation dissipation, conduction dissipation and radiation dissipation. But the universal formula for calculating evaporation coefficient established on this basis is imperfect since the temperature difference between water and air inadequately involved. Temperature difference between water and air is the driving force of conduction dissipation and induces matter transfer but not heat transfer. In experiment, evaporation and conduction are inseparable, therefore when the evaporation coefficient is calculated from the data and using evaporation equation, the temperature difference of water and air is included. The enthalpy difference formula is proposed to instead of the evaporation equation. By this method the said problem can be avoided.